Conventional air-source heat pumps lose 30-60% of their heating capacity when outdoor temperatures drop below freezing, often falling back on expensive electric resistance backup heat. In 2021, DOE launched the Residential Cold Climate Heat Pump (CCHP) Challenge to change that — pushing manufacturers to build systems that maintain full heating capacity at 5°F while using low-GWP refrigerants and supporting grid demand response. The results are now in, and commercial products are reaching the market (ACEEE, DOE).
The challenge specifications
DOE's specification, developed through workshops with industry partners starting in 2021, requires participating heat pumps to meet demanding cold-climate performance targets. At 5°F (-15°C), systems must deliver 100% of their rated heating capacity (compared to capacity at 47°F) and achieve a COP of at least 2.4 for systems rated 24,000-48,000 Btu/h, or 2.1 for larger systems. The compressor must start at temperatures at or below -5°F and continue operating down to -10°F. An optional extreme-cold target extends operation to -15°F with compressor cut-out at -20°F. Refrigerant GWP must not exceed 750 on a 100-year basis — ruling out R-410A (GWP 2,088) and requiring low-GWP alternatives like R-32 or R-454B. All systems must meet HSPF2 of 8.5 in Region V, maintain a turndown ratio of at least 30% at 47°F, and comply with ENERGY STAR demand-response requirements including general curtailment (≤70% rated power) and critical curtailment (≤40% rated power) (ACEEE).
Eight manufacturers, two rounds, 22 field sites
Eight manufacturers committed to the challenge: Bosch, Carrier, Daikin, Johnson Controls, Lennox, Midea, Rheem, and Trane. The first group (Lennox, Carrier, Trane, Rheem) completed laboratory testing in 2022 and began field testing in winter 2022-2023. The second group (Daikin, Midea, Bosch, Johnson Controls) completed lab testing in 2023 and started field testing in winter 2023-2024. Field validation covered 22 sites: 19 occupied single-family homes across the northern United States and 3 test homes at Natural Resources Canada in Ottawa. Data was collected at 1-second intervals for outdoor-unit and indoor-unit power, with outdoor temperature logged every 5 minutes. At least one year of data was captured for each site (ACEEE).
| Manufacturer | Round | Lab Testing | Field Testing |
|---|---|---|---|
| Lennox, Carrier, Trane, Rheem | 1 | 2022 | Winter 2022-2023 |
| Daikin, Midea, Bosch, Johnson Controls | 2 | 2023 | Winter 2023-2024 |
Results: all prototypes exceeded every target
In laboratory testing, all prototypes provided at least 100% of nominal rated heating capacity at 5°F — the core challenge requirement. All exceeded the COP target (2.1 or 2.4 depending on capacity class) at 5°F, making them more than twice as efficient as electric resistance heating (COP of 1.0). Several prototypes demonstrated heating operation at -15°F, meeting the optional extreme-cold target. All prototypes exceeded federal minimum standards (14.3 SEER2 cooling, 8.5 HSPF2 Region V heating) and demonstrated compliance with connected-product demand-response requirements (ACEEE).
In field testing, heating-season COPs ranged from 1.8 at -15°F to 3.5 at 45-55°F for compressor-only operation. Auxiliary electric heat contribution varied widely at very cold temperatures — from nearly 0% to as much as 90% — but generally decreased above 0°F as the heat pump handled more of the load. Homeowners reported improved comfort and satisfaction compared to their previous gas or electric furnace systems, with some noting increased airflow noise at very low temperatures due to higher CCHP airflow rates compared to furnaces (ACEEE).
The capacity revolution.Conventional heat pumps typically deliver only 40-70% of rated heating capacity at 5°F, with market-available cold-climate units averaging COPs of 1.75-2.25. The DOE Challenge required 100% capacity and COP above 2.4 — and every prototype met it. This means cold-climate heat pumps can now replace furnaces without relying on electric resistance backup, a breakthrough for residential electrification in northern states (ACEEE).
Commercial products arriving now
Several manufacturers have now begun selling residential cold-climate heat pumps that came out of the challenge. Product claims vary, so compare published low-temperature ratings, such as capacity and COP at 5°F, from the same test conditions. A claim that a unit "operates" at 5°F is not the same as delivering full capacity at 5°F.
On the commercial side, DOE's Commercial Building HVAC Technology Challenge is running in parallel. Rheem completed lab validation for a 10-14 ton rooftop heat pump that delivered 110% heating capacity at 5°F and 90% at -10°F, exceeding DOE efficiency benchmarks by 55% (IVEC), 20% (IVHEc), and 25% (COP2 at -10°F) (Contracting Business). LG also completed lab validation for a 10-ton heat pump rooftop unit, now in field trials at a retail store in Indiana and at Pacific Northwest National Laboratory in Washington, with testing continuing through 2027 (LG/PRNewswire).
What this means for homeowners and contractors
- Furnace replacement: Cold-climate heat pumps can now carry much more of the heating load in northern states, but whether one can fully replace a furnace depends on the home's measured heat loss. Field data showed backup heat doing anywhere from almost none to 90% of the heating in very cold weather (see the field follow-up below).
- Low-GWP refrigerant: The GWP ≤750 requirement means these systems use R-32 or R-454B, not R-410A — contractors need A2L training and compatible tools.
- Grid-interactive: All challenge systems support demand response, enabling utility programs that pay homeowners to reduce HVAC load during peak periods.
- Sizing matters: Even with 100% capacity at 5°F, proper Manual J load calculation remains essential — oversizing wastes efficiency, undersizing risks comfort at design temperature.
- Auxiliary heat strategy: Field data shows auxiliary heat use varies from 0% to 90% at very cold temperatures — thermostat setup and switchover settings dramatically affect operating costs.
- Commercial applications: Rooftop heat pump units delivering 110% capacity at 5°F open electrification opportunities for commercial buildings in cold climates.
Follow-up from the field
Technical review: Javier Santiago, New Jersey Master HVACR Contractor, Lic. #19HC00897200 · Reviewed Nov 2, 2026
How are cold-climate heat pumps holding up in North Jersey winters?
It depends heavily on sizing. Before replacing a furnace with a cold-climate heat pump, you need a proper Manual J load calculation to understand your home's envelope and heat loss. Here's a real-world example. Say you have an 80,000 BTU, 90% furnace (about 72,000 BTU of actual heat) and a 3-ton air conditioner. It's hard to say you can replace that with a heat pump that puts out about 36,000 BTU. Even if you get 40,000 BTU at 47°F, output drops toward 30,000 BTU as it gets colder. Can your house stay warm on 30,000 BTU at 10°F or 8°F? Those are the outdoor temperatures we design for in North Jersey. Only a thorough Manual J can answer that, and in some cases a blower door test.
Backup heat and dual fuel
In most cases, the best option is dual fuel: a heat pump paired with a natural gas furnace, if gas is available in your area. If not, electric backup heat is the alternative. With a really good cold-climate heat pump, the switchover to backup is usually around 20°F outside. But that depends on how the system was sized and whether it has enough BTUs to keep up with your home's heat loss. These things are much easier to get right in new construction than in a retrofit.
The installation mistakes I see most
Ductwork that isn't fully sealed. When a heat pump has little extra capacity on the coldest days, you can't afford to lose heat through the ducts. Most older North Jersey homes have systems that are way oversized, because they were sized to the original specs when the house was built in the '50s. Windows and doors, where a lot of air leakage happens, have improved a lot since then. Even so, you still need to make sure those gaps are covered. See our guide to duct leakage and sealing.
Not all "heats down to 5°F" claims are equal
Don't assume a heat pump from an online marketplace is apples to apples. Many heat pumps say they "heat down to 5°F" but don't say they heat at 100% capacity at 5°F. That's one of the biggest problems I see right now. Homeowners balk at the price of a true cold-climate heat pump because they've seen a cheaper unit that "heats to 5°F" and think it's the same thing. They're two different animals.
Reliability: the question nobody can fully answer yet
These systems may work well when they're new, but most brands don't have long-term durability data. Manufacturers with 20+ years of experience making inverter heat pumps have a longer track record than newer brands. With newer brands, ask: How reliable are they? How hard is it to find parts? How hard is it to find a technician who can troubleshoot them correctly? Weigh those questions first, when deciding whether a cold-climate heat pump is right for you, and again when choosing a brand and deciding what price makes sense.
Naming a product or manufacturer in this article is for identification purposes only and does not constitute an endorsement by HVAC Zone Inc. We are a multi-brand dealer and remain neutral on brand preference.
Considering a cold-climate heat pump for your home or building? Request a consultation — we evaluate your heating load, climate zone, and existing system to determine if a cold-climate heat pump is the right investment.